Many existing buildings throughout the world are in need of reinforcement to help them resist damage by earthquake, violent storms, acidic atmosphere, vibrations due to vehicle traffic, or similar threats. Many older buildings, especially, were designed to handle large compressive forces but are not resistant to lateral forces.
Buildings that are not resistant to sudden lateral force need to be reinforced for the safety of people who live or work in, or visit the building. Some buildings have considerable historical or artistic value and must be protected from disasters and environmental deterioration for their own sakes.
Some methods exist for reinforcing existing buildings. One that is used all over the world is wrapping a structure with fiberglass textile that is impregnated with epoxy. This method is taught in different forms in U.S. Pat. Nos. 5,043,033, 5,649,398, and 5,657,595. A means of connecting different components of a structure is taught in U.S. application Ser. No. 10/205,294, filed Jul. 24, 2002 and incorporated herein by reference.
The methods of U.S. Pat. Nos. 5,043,033, 5,649,398, and 5,657,595 are effective and can be performed with little intrusion on the occupants and visitors of the building being reinforced. A disadvantage to these methods is that they use some specialized materials that are not readily available in all locations. As a result, the materials are shipped from centralized distribution centers, sometimes to remote locations that are difficult to reach. The shipping and round transportation of heavy materials adds significantly to the cost of the project.
Another disadvantage of the wrapping methods is that the materials readily available on the market are not good matches in color and texture with old buildings. There are many buildings all over the world that are constructed of native stone, brick from local clay, or that are coated with plaster made with local minerals. As a result, the materials of the methods mentioned above, such as epoxy and fiberglass, may not match the color or texture of a given building.
Yet another disadvantage to the method discussed above is that some of the materials, particularly epoxy, are less fire resistant than conventional stone, brick, or plaster construction. It is desirable that a method for increasing a building's strength should also increase its fire-resistance, or at least not degrade it.
To avoid the disadvantage of the flammability of epoxy or other organic polymers, the textile could be coated with an inorganic hardenable paste such as mortar. However, this leads to a different disadvantage, which is that inorganic mortars are alkaline and tend to degrade ordinary fiberglass. Special alkaline-resistant glass textile is available, but is quite expensive. This incompatibility has discouraged the use of glass textile with mortar for reinforcement of structures. Graphite carbon or aramid fiber textiles would be compatible with mortar, but these textiles are also very expensive and not widely available in all countries.